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Regen question re: BTA on SGII

Discussion in 'Gen 2 Prius Technical Discussion' started by Neicy, Dec 15, 2008.

  1. Neicy

    Neicy Member

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    What is the maximum amps of regen that can be recovered by the battery before it begins to "throw away" energy? For example, if I have to brake harder than I planned, I have seen it go as high as -74 on the BTA x-gauge, but it seems I heard that there is a point where it begins to be converted to heat and I can't remember what that point is. Inquiring minds want to know. Thanks.
     
  2. josh2008

    josh2008 Active Member

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    I've seen the highest of 94 amps of regen. When I'm going down a slight incline I like to apply the brakes lightly to bring up the regen amps, I usually see 50-75 regen amps during this action.

    Hope this helps,
    Josh.
     
  3. hobbit

    hobbit Senior Member

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    I try to keep it under 50, but the max is theoretically 100 in
    optimal temperatures and it starts dropping when too cold or
    too hot. For example on a winter morning before the pack warms
    up a bit I can only do 50 amps of regen and then start see the
    brake pressure coming up.
    .
    _H*
     
  4. Kaos1

    Kaos1 Junior Member

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    Hobbit,

    How do you "see" the brake pressure increasing? Have you installed a pressure gauge on the brake line?

    Just curious as I have often wondered how to monitor this.

    Kaos1

     
  5. carz89

    carz89 I study nuclear science...

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    The max I've seen is also 94 amps charging. So my instinct tells me to apply the brakes not to exceed that number, since any more pressure is obviously wasted energy. However, the thing I'm not sure about is if and how much the brake pads are used if the brakes are lightly pressed to keep it under 94 amps. I think I read somewhere that the hydraulic brakes are not used except for hard braking (extrapolating beyond the regen limit) or for really low speeds (under 7 mph?).
     
  6. hobbit

    hobbit Senior Member

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    Toyota was kind enough to install pressure gauges on the brake
    lines for me; I see them with this.
    .
    _H*
     
  7. archae86

    archae86 Member

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    As others have said above, I think the limit is about 95 amperes, except when it is less. At least two reasons for it being less appear to be "too hot" and "too cold".

    So just managing to stay below 95 is not enough--when a lower limit applies you cannot get up to it. I try to notice if the displayed number fails to increase with increasing brake pressure, and figure that is the limit at the moment, and back off to stay below it if the road reality allows.
     
  8. Neicy

    Neicy Member

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    Thanks Hobbit. I thought it was around -50. BTW, how's the warm weather?